Luminaire



Dec- 1, 1964 G. P. WAKEFIELD ETAL 3,159,352

LUMINAIRE 4 Sheets-Sheet l Filed Nov. 16, 1960 FIG 2 INVENTORS GEORGE P. WAKEFIELD HARVEY H VICK ATTORNE YS De@ 1, 1964 G. P. WAKEFIELD ETAI. 3,159,352

LUMINAIRE 4 Sheets-Sheet 2 Filed Nov. 16, 1960 FIG 3 INVENTQR. GEORGE P. WAKEFIELD 8x HARVEY H.V|CK

ATTORNEYS De@ 1964 G. P. wAKEFlELD ETAL 3,159,352

LUMINAIRE 4 Sheets-Sheet 5 Filed Nov. 16, 1960 FIG 5 INVENTOR. GEORGE E wAKEFaELD e. HARVEY H. VICK BY Oberlm, [flaky e Dorme@ S UIOFlGT ATTORNEYS Dec. 1, 1964 G. P. WAKEFIELD ETAL 3,159,352

LUMINAIRE Filed NOV. 16, 1960 4 sheets-sheet 4 FIG IO Distribution Brigmnesses max av Candlepower Lnght Output Crosswise o 125 24.0% w 'enghwse x I 50o 90o 68.5 /o la! o g |200 44.5% J x A C G u u 57 (Perpendicutar) 8 1/C`- -58(Para||e|) 400 \`x---", K 56 4o 5o Go 7o 8o 90 30 DEGREES FROM NAD|R 5o INVENTOR.

.Z.9 GEORGE P. WAKEFIELD o4o 22.5% a HARVEY H. vlcK FIG 9 GMM mm2 DW ATTORNEYS United States 3,59,352 LUMiNAE George P. Wakefield and Harvey H. ich, Vermiiion, (Ehio, assignors, by niesne assignments, to Wakefield Corporation, Detroit, Mich., a corporation of Michigan Filed Nev. i6, 1956, Ser. No. 69,6@ 7 Claims. (Ci. 24d-53.11)

The present invention relates generally as indicated to a luminaire and, more particularly, to improvements in the refractor therefor and in the fixture body, as well.

It is a principal object of this invention to provide a luminaire having a transparent refractor that re-directs a considerable portion of the light flux upwardly at about a 45 angle, whereby, when the luminaires are mounted on stems beneath a room ceiling, the brightness difference between the ceiling and the luminaires is substantially reduced. Such re-direction of the light flux upwardly also tends to produce an even ceiling brightness between rows of on-ceiling mounted luminaries. Moreover, such redirection aids in brightness control at the sides of the luminaires and increases the overall efficiency by increasing the areas of the light transmitting media around the light sources.

It is another object of this invention to provide a luminaire in which the refractor thereof has narrow horizontal light transmitting bands parallel to the adjoining channel of the luminaire body so as to transmit direct upward linx to the ceiling in case single rows of luminaires are used, otherwise these areas on the ceiling are blacked out when such light-transmitting bands are omitted.

It is another object of this invention to provide a luminaire in which the refractor thereof has smooth exterior sides to facilitate cleaning, and the interior sides are prismatic to re-direct light downwardly and to retract light upwardly.

It is still another object of this invention to provide a luminaire in which the bottom of the refractor thereof has a simpliiied form of light control formation cornposed of crisscross rows of cones effective to provide for even brightness control.

It is still another object of this invention to provide a luminaire in which the refractor is partially luminous at its ends to transmit light endwise of the luminaire, whereby, in the case of continuous runs wherein two or more luminaires are mounted in end to end relation, the joints will be luminous, and unnoticeable.

It is still another object of this invention to provide a luminaire of the character indicated which has a built-in channel which is exteriorly shaped for accommodating longitudinally adjustable clamp-on fittings for ceiling or stern mounting, and which is interiorly shaped for detachable engagement by a snap-in cover that serves as a reilector between the lamps and as a cover for the ballast mounted in the channel and that forms a Wireway with e channel.

It is yet another object of this invention to provide a simple form of luminaire and refractor therefor which is inexpensive to manufacture and with which superior light control is achieved.

It is still another object of this invention to provide a luminaire of the character indicated which has a novel form of lamp holder support structure removably attached at each end of the luminaire body.

It is still another object of this invention to provide a luminaire in which the refractor thereof is yieldably held in place against vibration and air currents and is mounted for downward swinging movement (and removal, if desired) from either of its upper edges to facilitate re-lamping and other service.

Other objects and advantages of the present invention 3,l59,352 Patented Dee. l, i954 ice will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises lthe features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of ythe invention, these being indicative, however, of a few of the various ways in which the principle of the invention may be employed.

ln said annexed drawings:

FIG. l is a perspective View of a preferred embodiment of this invention and being broken away in part to clearly show the internal construction of the luminaire;

FIG. 2 is a fragmentary longitudinal cross-section view taken substantially along the line 2 2, FIG. 3 from about the middle of the luminaire toward one end to show how the ballast is mounted and enclosed in the channel, to show one of the stabilizing protuberances for on-ceiling mounting, and to show one of the wire lead retainers;

FG. 3 is a transverse cross-section view of the luminaire herein taken substantially along the line 3-3, FIG. 2 and showing (in dotted lines) how the refractor is swung down about either one of its top edges for relamping or other purpose;

FiG. 4 is a fragmentary longitudinal section view on enlarged scale taken through one end of the luminarie substantially along the line 4-4, FIG. l;

FIG. 5 is a fragmentary longitudinal cross-section View showing a luminaire to accommodate refractors in end to end relation;

FIG. 6 is a much enlarged fragmentary cross-section view illustrating the conical formation at the bottom of the refractor, such section having been taken substantially along the line 6 6, FIG. 4;

FIG. 7 is a bottom plan view as viewed upwardly in FIG. 6;

FIG. 8 is an enlarged cross-section view of a portion of the refractor herein showing how the principal light rays are reflected and refracted; and

FIGS.,9 and 10 are typical vcandlepower distribution and brightness graphs respectively of the luminaire embodying the present invention.

Referring now in detail to the drawings, and first more especially to FIG. 1, the luminaire 1 herein comprisesY a body or channel and reflector assembly 2 with end caps 3 at each end against which lamp holders 4 in supports 5 (see FIG. 4) are positioned for engagement with the terminals of fluorescent or like lamps 6; and a refractor 7 supported by said assembly 2 and having opposite p downwardly divergent sides 8 which are interiorly grooved to form reliecting and refracting prisms, and a bottom brightness control surface 9 composed of crisscross rows of cones 10 (see FIGS. 6 and 7) intersecting one another to provide square bases when Viewed upwardly from beneath the luminaire 1.

The refractor 7 is preferably injection molded of crystal acrylic plastic to provide transparent sides 8 and bottom 9 and -to provide frosted or translucent ends il with the translucent portion extending to the bottom tangent lines of the refractor as denoted, for example, by the reference numeral 12 in FIG. 4. Such plastic (methyl methacrylate) has excellent molding properties, and other properties such yas tensile, flexural, and impact strengths, low water absorption, good'sunlight resistance, and high transparency 92% light transmission) to make it a superior material for the manufacture of instant refractor 7. This material has a refractive index of 1.49.

The reiiector and channel assembly 2 includes a body member i4 as of formed sheet metal having a central downwardly open channel l5 of which the upper side portions 16 converge downwardly to receive conventional clamp-on type fittings 17 (see FIG. 3).' The body mem- 'ber 14 has upwardly diverging relecting surfaces 1S, a pair of upwardly opening grooves 19 in either of which the corresponding edge of the refractor 7 is received for swinging movement as later explained in detail, and a pair of horizontally disposed refractor support llanges 2.0 which are downwardly oiset so as to provide Shoulders 21 for centering the refr'actorV 7.

As shown, the upper side portions 16 of the channel 15 form catches to yieldably receive the longitudinal ribs 'Y 23 along the upper edges of the snap-in cover member 24' whichhas a V-shaped bottom portion to provide continuations of the surfaces 18 of the body'm'ernber 14. Thus',

Ywith the cover member 24 snapped into place in channel 15 there is formed therebetween a closed-wire way and,

Vin addition, the cover member 24 is formed with longitudinally extending bulges 25 at about the mid-portion of the length thereof to accommodate the lighting fixture ballast 26 which may be held in place as by a tongue 27 struck down from the web of the channel 15 to receive the ange at one end of the ballast (see FIG. 2), and by a screw and nut assembly 23 extending through the flange at the other end ,of the ballast. A Y The -body member 14 may be formed with stabilizing protuberances 29 near the ends for engagement with the room ceiling when the luminaire is attached directly to the ceiling. Y

Extending crosswise of the channel 15 beyond the ends of ballast 26 are Wire lead retainers 30 (see FGS. 2 and 3).

As best shown in FIGS. 3 andv4, at eachend of the channel and reflector assembly 2 is an end plate 3 which hasV an inturned top llange 31 attached as by rivets 32.

Inside each end plate 3 is a lamp holder support 5. which has a bottom outwardly extending flange E4 toV which a'leaf spring member 35 is riveted as shown, and intermediate side lugs 36 which are bent outwardly and threaded, whereby screws 37 may be employed to secure the respective lamp holders 4 in place.

Each lamp holderl support has a top inwardly extending flange SS'Which is yieldably held Aby a hooker catch member 39 struck out from the body member 14. Each end plate 3 and lamp holder support S may be provided with the usual knock-outs (not shown) for wires,

but to impart decorative inlluence to the luminaire, there may be affixed on each end plate`3 a suitable knock-out cover 49 as of aluminum foil orthe like. Also, for additional aesthetic purpose each'end plate3 may be formed vwith a small opening 41 therethrough and on the'rear side, there may be attached a-transparentcolored pressure sensitive disk 42 which may be of any desired color.

2. to be replaced, the right :flange 45 of the reractor 7 will i be positioned ,in the right groove 19 so that the refractor 1 will swing down' in the opposite direction. Of course, if it is desired to remove the refractor 7, ths can be done by moving the refractor to disengage the llange 45'frcm the groove 19. v Y Y Referring now to the refractor 7 in detail, it is as aforesaid, preferably injection molded'of crystal acrylic plastic of say about 1A; thickness. The Vinternal longitudinalV ribs orprisms 47 along the opposite sides 8 are about .06"

. depth. Similarly, the cones l0 arranged in crisscross rows on the bottom 9 of the refractor 7 are of about .06 altitude'and have apex angles of about 104. in practice,

the die for molding the refractor 7 is made to form the l i bottom surface of the refractor as by employing the point of a ydrill having a 104 point angle and of diameter at least about 1%@ of an inch but the rows are spaced apart.

' both longitudinally and crosswise only .153 thus to form crisscross rows of cones which,l when viewed from the bottom upwardly, appear as having square'bases as most clearly shown in FIG. 7. Y Y

With respect to the prisms 47 on the inside, these are of generally sawtooth form with an included angle 48 of about 70 with one side 4i? at an angle of about 30 from the respective sides 8. In turn, the sides d are sloped downwardly and outwardly at an angle of about from vertical and the bottom 9 slopes downwardlyV and inwardly from each side toward the center at an angle of about 5. The prisms47, or ribs', at the rounded lower corners of the refractorg are of about 55 included angle 50 for the rst one, and of about includedangle for the secand and third ones, 'the first one being ot aboutz depth,

Y the second one of about Ms" depth, and the third one of i r about 5/32 depth as measured generally horizontally in FIG. 8.

Thus, it can-be seen from FIG. 8 that by-providing' the internal longitudinal prisms yd'7 along the downwardly and .outwardly diverging sidesS of the refractor 7 and byproviding the bottom formation of crisscross'rowsof Insofar as the refractor 7 is concerned, andasipre-' viously mentioned, it has opposite downwardly diverging sidesS, the'upper ends of which terminate in horizontal inturned flanges 45 which are adapted to rest on the horizontalilanges 20 ofthe body member 14, and by reason Y of the step Z1, the retract-m7 is thereby centered with respe'ctV tothe channel'rand reflector assembly 2. The open ends of the refractor 7. are of less height and width than.

' l"the end plates 3 and the edge-s 46'arerengaged by the leaf Vsprings 35 l.to yieldably hold the flanges 45 and 20' in engagement.

When itis desired to service the luminaire y1, all that l one has to do is to litt keither side yof the refractor 7 to position the flange 45 above the corresponding step 2l andY to shove the thus-lifted side of theV refractor toward the* rellector assembly V2, whereupon theV lifted'flange 45' is Ydisposed in the groove 19011 that side of the luminaire and retained ytherein bythe top lllanges 31 ot the end plates 3 which overlieportions of the; grooves 19." Accordingly,

v when the opposite side'of the refractor 7 is allowed to drop esY 70.Y opaque end caps coextensive -yvitli the end faces of the i down, its other anger45 willclearthe other ange 20 so i right-hand lamp s.simiiar1y,-if ,thaise-hanen@ s s l vthatrthe retractor 7 willrswing tothe dotted line posi- 'tionshown in FIG. v3 thus,- providing ready access Vto 'the cones 10, the principal` light raysV from each lamp 6- will be rellected and retracted as indicated by the numerous lines and arrows. Specifically, with a luminaire 1 of the typey herein disclosed having the refractor 7 herein, ythe average brightness curves 55 Vand S6 of FIG. l0,

crosswise and lengthwise respectively, at from 45 to 90 from nadir indicatev an average brightness crosswise `(curve S5 which is a minimum of about 400 footlamberts at about irorn'nadir, andan average brightness lengthwise A(curve 56) which is of generally similar character- .i

Y varies` from about 900 footlambertsat 45 to about 30D-400 footlarnberts at 65, 75 and V85, and thencev Vdrops to aboutr250 footlamberts at I y At 0 at thevr centerline of the luminaire the brightness is660 foot- -l'amberts' and at 0 ldirectly `beneath theV lamps @,fthe f brightness is'2,020 `footlarnberts. Now, insofar as ,theV light Vdistribution curves V5'7 (prer-V pendicular)V and 5S (paralleU-'ar'e concerned as shown in FIG.V 91about 241.0% ofthe light outputis upward, if Y In'th'e zone from 0 to 40?, the light `output is'22.5% and in I Vthe'zone from 0fto 60, the light outputy is-35`.0%.

' In contrast, in a 'comparable lixture 'having vertical and 44,5%VVV of the light output is downward.

parallelsidesron the Vcle'ar'"plastic refractor thereof and refractor have averageV crosswise' brightnesses which Vgreatlyv increase from 60 to 90 from nadir from Vabout 800' footlarnbertstoabout 15,00 footliamberts and average lengthwise-brightness@ whichfdecrease from about k900 S footlamberts at 45 to about 300 footlambert's at 80. Moreover, in such luminaire, only 9% of the light output is upward, whereas 55.5% of the light output is downward.

The foregoing test results on the present luminaire 1 are based on a white enameled metal housing assembly 2 having a reflectance of about 0.90 and on two 20 watt fluorescent lamps 6 with a light output of 1380 lumens and identiiied as 24" T12 Standard Warm White Fluorescent Lamps. Candlepower distribution was taken in three vertical planes intersecting in the plane of the face of the refractor 7 and the test distance was 25 feet. Following is a chart plotting mid-zone candlepower at diier'ent horizontal angles in relation to mid-zone angles:

Mid-Zone Caudlepower- Horizontal Angles Angle, Mid-zone, degrees Parallel 45 Perpen- Lumens dicular Generally, the luminaire l will be of 48" length using 40 watt, 2760 lumens, 48 T12 fluorescent lamps but when the length of the luminaire 60 is to be a multiple of the length of the refractor 7, it is preferred to use a continuous body member 61 as shown in FIG. 5, and to provide a single thin end plate 62 between the refractors 7 which has an ear 63 secured to the body member 61 as by means of the screw 64, but otherwise the lamp holder supports and lamp holders 4, as well as the leaf springs 3S etc., are of the same structure as described in relation to the single length luminaire 1 and thus the same reference numerals have been used to denote the same parts to avoid necessity of repeating the description of the structure and operation of the FIG. 5 embodiment.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

We therefore particularly point out and distinctly claim as our invention:

l. A luminaire comprising an elongated body member having downturned outturned flanges along its opposite edges vand downturned plates at its ends; lampholders secured to said luminaire between said plates for receiving a tubular lamp therebetween; a light transmitting refractor having inturned anges along its opposite upper edges straddling said downturned lianges and resting on the respective outturned anges and opposite sides and a bottom enclosing such lamp; said body member being formed with upwardly opening longitudinal grooves inwardly adjacent the respective downturned anges to receive the corresponding inturned ange upon lifting 2. The luminaire of claim 1 wherein the central portion of said body member inwardly of said upwardly opening longitudinal grooves is formed as a downwardly open longitudinally extending channel in which a ballast for such lamp is mounted and in which `the ballast leads and lamp wiring are disposed; and wherein a cover member is detachably tted in such channel to conceal said ballast, leads, and wiring, said cover member and body having substantially coplanar inclined surfaces to reflect light emanating from such tubular lamp.

3. The luminaire of claim 1 wherein the opposite sides of said refractor are formed with internal longitudinally extending ribs that constitute prisms to refract light emanating from such lamp in an angularly upward direction; 'and wherein the bottom of said refractor is formed with crisscross rows of cones effective to substantially reduce lengthwise and crosswise brightness of the luminaire when viewed upwardly at angles greater than about 45 from nadir.

4. The luminaire of claim l wherein said refractor has light transmitting ends disposed between said downturned plates and extending inwardly from the sides and upwardly from the bottom to the sides and bottoms of the perim- :yieldably bearing down on such upwardly extending end and lateral shifting of that side of said refractor over the eters of the respective plates; and wherein spring means on said plates yieldably bear down on such upwardly extending end portions to yieldably hold said inturned flanges against said outturned anges.

5, The luminaire of claim 1 wherein the opposite sides of said refractor ldiverge downwardly and outwardly and are formed with internal longitudinal ribs that constitute prisms to refract light emanating from such lamp angularly upward.

6. A luminaire comprising an elongated sheet-metal body member having a central, longitudinally extending, and downwardly open channel of which the upper edges converge downwardly; complemental converging luminaire support clamps longitudinally adjustably clamping said converging upper edges of said channel; an upwardly open channel-shaped cover member having a detachable snap connection within the upwardly diverging upper edges of the channel of said body member to form a wireway; lampholders secured to said body member adjacent the ends of the latter for receiving a tubular lamp therebetween and operatively connected to electric wiring in such wireway; and a light transmitting refractor supported by said body member, said refractor having opposite sides and a bottom enclosing such lamp.

7. A luminaire comprising an elongated body member having downturned and outturned flanges along its opposite edges and downturned plates at its ends; pairs of lampholders secured to said luminaire between said plates for receiving a pair of parallel tubular lamps therebetween; said bodyv member being formed with a central downwardly open longitudinal channel inwardly of said downturned and outturned flanges; a cover member having detachable engagement with said channel to form a ballast chamber and a wireway; said body member and cover member defining a longitudinal V-shaped reilector between such lamps; a light transmitting refractor having inturned flanges straddling said downturned anges and resting on the respective outturned flanges and opposite sides and a bottom enclosing such lamps, said refractor having light transmitting ends disposed between said plates and extending inwardly from the sides and upwardly from the bottom to the Sides and bottoms of the perimeters of the respective plates; and spring means onsaid plates portions to yieldably hold said inturned flanges against said outturned anges.

References Cited in the tile of this patent UNITED vSTATES PATENTS 1,677,074 corcoran July 1o,` 192s Cole` June 30, 1930 Harris V Oct, 2,.

Yi956 l@ 1,247,350v

Zingone Mar.v 4, 1953 Lipscomb vv June 3, 1958 Y, Friz-zell et al. j Aug.v 5, 1958 Y Pincha et l. Apr. V21, 1959 Franck A V "May 1-9, 1959 Y Guth Sept- 15, 1959 Young Aug. ,'20, 1963 Y lFOREIGN PATENTS France Ot. 24,7196@ 

7. A LUMINAIRE COMPRISING AN ELONGATED BODY MEMBER HAVING DOWNTURNED AND OUTURNED FLANGES ALONG ITS OPPOSITE EDGES AND DOWNTURNED PLATES AT ITS ENDS; PAIRS OF LAMPHOLDERS SECURED TO SAID LUMINIARE BETWEEN SAID PLATES FOR RECEIVING A PAIR OF PARELLEL TUBULAR LAMPS THEREBETWEEN; SAID BODY MEMBER BEING FORMED WITH A CENTRAL DOWNWARDLY OPEN LONGITUDINAL CHANNEL INWARDLY OF SAID DOWNTURNED AND OUTTURNED FLANGES; A COVER MEMBER HAVING DETACHABLE ENGAGEMENT WITH SAID CHANNEL TO FORM A BALLAST CHAMBER AND A WIREWAY; SAID BODY MEMBER AND COVER MEMBER DEFINING A LONGITUDINAL V-SHAPED REFLECTOR BETWEEN SUCH LAMPS; A LIGHT TRANSMITTING REFRACTOR HAVING INTURNED FLANGES STRADDLING SAID DOWNTURNED FLANGES AND RESTING ON THE RECEPTIVE OUTTURNED FLANGES AND OPPOSITE SIDES AND A BOTTOM ENCLOSING SUCH LAMPS, SAID REFRACTOR HAVING LIGHT TRANSMITTING ENDS DISPOSED BETWEEN SAID PLATES AND EXTENDING INWARDLY FROM THE SIDES AND UPWARDLY FROM THE BOTTOM TO THE SIDES AND BOTTOMS OF THE PERIMETERS OF THE RESPECTIVE PLATES; AND SPRING MEANS ON SAID PLATES YIELDING BEARING DOWN ON SUCH UPWARDLY EXTENDING END PORTIONS TO YIELDING HOLD SAID INTURNED FLANGES AGAINST SAID OUTTURNED FLAGES 